Systems are available for the draining of fields having different elevations. In general, the overall object is to maintain water at the root zone of the crop to promote growth, but to avoid excess water, which is harmful to crops. Typically, a manually operated valve is provided with a housing incorporating an outlet pipe which may feed a drainage ditch or other water tributary. The crop field in which it is desired to control the drainage, is provided with a principal or “main” drain tile and a network of drainage tile tributaries (called “lateral lines” or simply “laterals”) joined to the main line and extending up the various elevations of the field desired to be drained. This type of system has certain disadvantages, primarily in that, as is well known, land at higher elevations is consistently drier than land at lower elevations. This is because in a typical arrangement of drain tiles, all of the tiles (or lines) are open at all times, and the only means of control is a manual valve that controls flow through the outlet pipe. Thus, water flows (underground) continuously to lower levels under gravity as long as the manual valve is open, thereby leaving higher elevations to be depleted of water and therefore become dry sooner than lower levels.